1. Field of the Invention
This invention relates to a photovoltaic element and a method for manufacturing the same, particularly to a photovoltaic element and a manufacturing method of the photovoltaic element which are suitable for semiconductor elements to constitute a solar battery.
2. Related Art Statement
Attention has been paid to a thin film solar battery formed by a vapor phase epitaxy method, and various research and development are carried out for the thin film solar battery. Generally, the thin film solar battery is composed of a photovoltaic element in which a transparent conductive film, a first conduction-type semiconductor layer, an intrinsic semiconductor layer and a second conduction-type semiconductor layer are stacked on a transparent substrate in turn.
FIG. 1 is a structural view showing a conventional photovoltaic element.
In a photovoltaic element 10 depicted in FIG. 1, a transparent conductive film 2, a p-type semiconductor layer 3, an intrinsic semiconductor layer 4, a n-type semiconductor layer 5 and a backside electrode 6 are stacked on a transparent substrate 1.
The transparent substrate 1 is composed of a glass substrate or a resin film made of polyethylene naphthalate (PEN), polyethersulfone (PES), polyethylene terephthalate (PET) or the like.
The transparent conductive film 2 is formed, of tin oxide, ITO, ZnO or the like, in a thickness of about 1 μm or below by sputtering or firing.
The p-type semiconductor layer 3, the intrinsic semiconductor layer 4 and the n-type semiconductor layer 5 are formed in a thickness of about 1 μm or below by plasma CVD, etc. These semiconductor layers include a Si semiconductor material as a base matrix. The p-type semiconductor layer also includes a dopant such as B, and the n-type semiconductor layer also includes a dopant such as P.
The backside electrode 6 is formed, of a metallic material such as Al, Ag, or Ti, in a thickness of about 100 μm or below by sputtering or evaporation.
However, the photovoltaic element 10 has the transparent conductive film 2, on which the above semiconductor layers are formed, and therefore, has a lower open circuit voltage (Voc) than that of a photovoltaic element having a metallic electrode on which the above semiconductor layers are formed.